(Trifluoromet hylphenoxy)-phenylurea compounds and herbicidal compositions

Preparation of N,N-dimethyl-N'-[3-chloro-4-(3-trifluoromethyl-phenoxy)-phenyl]-urea ##STR6##

Phosgene was introduced into 20.1 g (0.07 mole) of 3-chloro-4-(3-trifluoromethyl-phenoxy)-aniline, dissolved in 200 ml of chlorobenzene, at -5° C for 1 hour. The reaction mixture was then warmed slowly and the introduction of phosgene was repeated at 120° C until the reaction mixture had become a clear solution. Nitrogen was then passed over it for half an hour to remove remnants of phosgene; dimethylamine was then introduced at 0° C until the reaction mixture showed a basic reaction. After stirring for one hour at room temperature, the bulk of the chlorobenzene was distilled off and the residue was recrystallized from a little acetonitrile.

16 g (65% of theory) of N,N-dimethyl-N'-[3-chloro-4-(3-trifluoromethyl-phenoxy)phenyl]-urea were obtained in the form of white crystals of melting point 166° C.

The following compounds were obtained analogously to Example 1 in accordance with process variant (a):

Table

______________________________________

Melting

Ex. point

No. Structural formula (° C)

______________________________________

##STR7## 173

3

##STR8## 152

4

##STR9## 130

5

##STR10## 173

6

##STR11## 178-180

7

##STR12## 130

8

##STR13## 118

______________________________________

(Process variant (b)) -- Preparation of N,N-dimethyl-N'-[4-(2-chloro-4-trifluoromethylphenoxy)-phenyl]-urea ##STR14##

13 g (0.14 mole) of dimethylcarbamic acid chloride were added dropwise to 29 g (0.1 mole) of 4-(2-chloro-4-trifluoromethyl-phenoxy)-aniline, dissolved in 50 ml of pyridine, at 0° C. The mixture was warmed to 70°-75° C for half an hour, the bulk of the pyridine was stripped off in vacuo and the residue was poured into water and acidified with dilute hydrochloric acid. The precipitate was filtered off, dried and recrystallized from toluene. 29 g (89% of theory) of N,N-dimethyl-N'-[4-(2-chloro-4-trifluoromethylphenoxy)-phenyl]-urea were obtained as pink crystals of melting point 140° C.

(Process variant (c)) -- Preparation of N-methyl-N'-[3-chloro-4-(3-trifluoromethylphenoxy)-phenyl]-urea ##STR15##

18.7 g (0.06 mole) of 3-chloro-4-(3-trifluoromethylphenoxy)-aniline were dissolved in 100 ml of acetonitrile, and 3 drops of triethylamine and 4.3 g (0.078 mole) of methylisocyanate were added at 10° C. The mixture was stirred for a further 4 hours at room temperature and then poured into water, and when the reaction mixture had crystallized throughout the solid was filtered off and recrystallized from toluene. 6 g (29% of theory) of N-methyl-N'-[3-chloro-4-(3-trifluoromethylphenoxy)-phenyl]-urea of melting point 160° C were obtained.

The following compounds were obtained analogously to Example 10 in accordance with Process variant (c):

______________________________________

Melt-

ing

Ex. point

No. Structural formula (° C)

______________________________________

11

##STR16## 119

12

##STR17## 173

13

##STR18## 217

14

##STR19## 188

15

##STR20## 230

16

##STR21## 155

______________________________________

The preparation of the intermediates were carried out, for example, as follows: ##STR22##

32.5 g of potassium hydroxide flakes in 30 ml of water were added to 54.5 g (0.5 mole) of 4-aminophenol dissolved in 350 ml of dimethylsulfoxide, and 150 ml of a water/dimethylsulfoxide mixture were distilled off in vacuo at 15-20 mm Hg. 125 g (0.5 mole) of 1-trifluoromethyl-3,4,5-trichlorobenzene [n D 20 : 1.5008 67- 68% of theory, compare J. Am. Chem. Soc. 57, 2066-2068 (1935) and U.S. Pat. No. 2,654,789] were then added to the reaction mixture at about 70°-80° C and the mixture was stirred for a further 2 hours at 120°-130° C. The substance was precipitated with water, filtered off, washed with water and recrystallized moist from an ethanol/water mixture, thus giving 40-50% of theory of 4-(2,6-dichloro-4-trifluoromethylphenoxy)-aniline of melting point 128°-130° C.

The following intermediates were prepared analogously:

______________________________________

Physical data

(melting point,

Structural formula refractive index)

______________________________________

##STR23## 205-210° C (from water)

##STR24## 131-136° C

##STR25## 220° C

##STR26## 200-210° C (from ethanol)

##STR27## 205-215° C (from 50% strength ethanol)

##STR28## 74-76° C (from cyclohexane)

##STR29## 76-77° C (via the hydrochloride, from

ethanol)

______________________________________

The active compounds according to the invention have a very good herbicidal activity and can therefore be used for combating weeds.

Weeds in the broadest sense are to be understood as all plants which grow in locations where they are not desired.

Relevant weeds are, in particular: dicotyledons, such as mustard (Sinapis), cress (Lepidium), cleavers (Galium), chickweed (Stellaria), camomile (Matricaria), gallant soldier (Galinsoga), goosefoot (Chenopodium), annual nettle (Urtica), knotgrass (Polygonum), groundsel (Senecio) and rough-haired amaranth (Amaranthus retroflexus); monocotyledons, such as timothy (Phleum), bluegrass (Poa), fescue (Festuca), goosegrass (Eleusine), foxtail millet (Setaria), ryegrass (Lolium), cheat (Bromus), barnyard grass (Echinochloa), wild oats (Avena fatua), slender foxtail (Alopecurus) and Johnson grass (Sorghum halepense).

Some of the active compounds according to the invention are particularly suitable for the selective combating of weeds, for example in carrots.

The active compounds according to the present invention can be converted into the usual formulations, such as solutions, emulsions, suspensions, powders, pastes and granulates. These may be produced in known manner, for example by mixing the active compounds with extenders, that is, liquid or solid or liquefied gaseous diluents or carriers, optionally with the use of surface-active agents, that is, emulsifying agents and/or dispersing agents and/or foam-forming agents. In the case of the use of water as an extender, organic solvents can, for example, also be used as auxiliary solvents.

As liquid diluents or carriers, there are preferably used aromatic hydrocarbons, such as xylenes, toluene, benzene or alkyl naphthalenes, chlorinated aromatic or aliphatic hydrocarbons, such as chlorobenzenes, chloroethylenes or methylene chloride, aliphatic hydrocarbons, such as cyclohexane or paraffins, for example mineral oil fractions, alcohols, such as butanol or glycol as well as their ethers and esters, ketones, such as acetone, methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone, or strongly polar solvents, such as dimethyl formamide, dimethyl sulfoxide or acetonitrile, as well as water.

By liquefied gaseous diluents or carriers are meant liquids which would be gaseous at normal temperatures and pressures, for example aerosol propellants, such as halogenated hydrocarbons, for example freon.

As solid diluents or carriers, there are preferably used ground natural minerals, such as kaolins, clays, talc, chalk, quartz, attapulgite, montmorillonite or diatomaceous earth, or ground synthetic minerals, such as highly-dispersed silicic acid, alumina or silicates.

Preferred examples of emulsifying and foam-forming agents include non-ionic and anionic emulsifiers, such as polyoxyethylene-fatty acid esters, polyoxyethylene-fatty alcohol ethers, for example alkylarylpolyglycol ethers, alkyl sulfonates, alkyl sulfates and aryl sulfonates as well as albumin hydrolyzation products; and preferred examples of dispersing agents include lignin sulfite waste liquors and methyl cellulose.

The active compounds of this invention may be present in the formulations in admixture with other active compounds.

The formulations in general contain from 0.1 to 95 percent by weight of active compounds, preferably from 0.5 to 90 percent by weight.

The active compounds can be used as such or in the form of their formulations or as the use forms prepared therefrom, such as ready-to-use solutions, emulstions, suspensions, powders, pastes and granules. They may be used in the customary manner, for example by spraying, atomizing, dusting, scattering and watering.

The active compounds according to the invention can be employed both in the pre-emergence process and in the post-emergence process. Preferably, they are employed in the post-emergence process.

The amount of active compound employed can be varied within fairly wide ranges. It depends essentially on the nature of the desired effect. In general, the amounts used are between 0.1 and 25 kg/hectare, preferably between 0.3 and 10 kg/hectare.

The active compounds according to the invention in part also display a fungicidal activity. They are, in particular, active against rust diseases; thus, for example, it is possible to treat shoots to protect them against Puccinia triticina.

The present invention also provides a herbicidal composition containing as active ingredient a compound of the present invention in admixture with a solid or liquefied gaseous diluent or carrier or in admixture with a liquid diluent or carrier containing a surface-active agent.

The present invention also provides a method of combating weeds which comprises applying to the weeds or a weed habitat a compound of the present invention alone or in the form of a composition containing an active ingredient a compound of the present invention in admixture with a diluent or carrier.

The present invention further provides means of yielding crops protected from damage by weeds by being grown in areas in which immediately prior to and/or during the time of the growing a compound of the present invention was applied alone or in admixture with a diluent or carrier. It will be seen that the usual methods of providing a harvested crop may be improved by the present invention.

The herbicidal activity of the present compounds is illustrated by the following biotest Example, in which the active compounds of this invention are each identified by the number of the corresponding preparative Example hereinafter.